The present invention concerns a system for evaluating the geometry of articles transported by a conveyor, such as fruit in a crate resting on a conveyor.
A system of the above kind is used in particular in an installation for automatically labelling fruit in crates.
In an installation of the above kind, crates containing fruit to be labelled travel on a conveyor belt that is driven continuously. The fruit is distributed over most of the surface of the crate with the individual fruits held side-by-side in a particular arrangement. To this end the individual fruits are received in adjacent cells disposed in rows and columns in the crate, for example.
Above the conveyor are successively disposed a system for evaluating the geometry of the fruit in the crates and a labelling system.
The labelling system includes labelling heads distributed transversely across the width of the conveyor. Each head is associated with one row of fruit in a crate. Accordingly, for satisfactory labelling, the labelling heads must be spaced by the distance between the rows of fruit in the crates.
To enable fruit of different sizes or differently arranged in the crates to be labelled, the transverse position of each labelling head relative to the conveyor is adjustable. The height of the labelling heads is also adjustable. The position of the labelling heads is adjusted by motor-drive means controlled by a central control unit. The position of the labelling heads is modified according to the geometry of the fruit in the crates.
In prior art installations the systems for evaluating the geometry of the fruit in the crates include one or more video cameras disposed above the conveyor. The cameras are adapted to produce images of the crates containing the fruit. They are connected to a central data processor unit using image processing algorithms to deduce the geometry of the fruit and their position in the crates from the images of the crates.
Such algorithms are .extremely complex and the resulting evaluation of the geometry is unreliable. It is extremely difficult to distinguish between the components of the crate and the fruit in the images of the moving crates.
Accordingly, the solutions currently known in the art are very costly, difficult to use and not very reliable.
The object of the invention is to propose a system for evaluating the geometry of articles which is simple to implement and which in particular requires less complex processing algorithms.
To this end, the invention provides a system for evaluating the geometry of articles such as fruit transported by a conveyor, characterized in that it includes:
a frame adapted to be mounted facing the conveyor,
at least one feeler carried by the frame and moved relative to the frame by articles transported by the conveyor, the or each feeler having an end for tracking the exposed surface of an article while it is being transported by the conveyor, which tracking end is adapted to rest on the article and to move the feeler relative to the frame by an amount representative of the position relative to the conveyor of the point on the article to which the tracking end of the feeler is applied,
means for measuring the position of the or each feeler relative to the frame, and
means for calculating the geometry of the articles according to the measured position of the or each feeler.
In particular embodiments of the invention, the system has one or more of the following features:
it includes a set of feelers distributed across the width of the conveyor;
the or each feeler includes a lever articulated to the frame about an axis substantially perpendicular to the direction of forward movement of the conveyor;
said measuring means include, for each feeler, a potentiometer disposed between said feeler and the frame;
said measuring means include a video camera fixed relative to the frame and adapted to observe the movement of a marked region of the or each feeler and image processor means adapted to deduce the position of each feeler from said position of the marked region in the image; and
said marked region is formed by the end of the lever forming a feeler opposite the end for tracking the articles.
The invention also provides an installation for labelling articles, including a conveyor for transporting the articles above which are disposed, in the direction of forward movement of the conveyor, a geometry evaluation system according to any preceding claim and a labelling system including a plurality of labelling heads mobile transversely across the width of the conveyor, the installation further including a central data processor unit adapted to control the position of the labelling heads as a function of the geometry of the articles to be labelled evaluated by the evaluation system.
In particular embodiments of the invention the installation has one or more of the following features:
the labelling system includes means for adjusting the height of the labelling heads relative to the conveyor and at least one member for pressing down the labels, disposed to the rear of the labelling heads relative to the direction of forward movement of the conveyor and adapted to be moved in the heightwise direction with said labelling heads; and
said pressing member is a motor-driven roller whose rotation speed is synchronized with the speed of forward movement of the conveyor.